Mii brawler is kind of top tier until the opponent stops getting caught by dthrow -> up-b at the ledge and acknowledges he has absolute garbage kill options and nothing to kill or set up kills off a throw, then he falls to being just above average.
Edit: Was responding to solidsense
Eh...
Well, first off, "stop getting caught by dthrow -> up-b at the ledge" is harder than it looks. Kind of like saying "stop getting caught by Diddy's DThrow". Except without bananas and with a guaranteed NAir conversion. Oh, plus one of the best mobility characters in the game, if not the best. (Assuming this is Short/Thin or even Short/Fat here, as if not, hard to take Brawler discussion seriously otherwise.)
He doesn't have the issue of "having garbage kill options". He actually just lacks safe ones. Only DSmash is pretty safe to throw out, his DAir and BAir are the only aerials with kill potential (albeit they aren't even that strong unless offstage), and his specials are punishable or short in range. He has no issues with strong kill moves, though. He's just limited in number there and has to space them very close to his opponent. He's no Captain Falcon, sure. But FSmash, USmash (somewhat), DSmash (back hit), Helicopter Kick, Ultimate Uppercut, and Onslaught have plenty of power and can kill at relatively early percentages. And they aren't hard to hit with. You just need to make sure that you're going to hit with them, so patient usage of certain moves is a must (outside of combo KO's).
Not sure what you meant by "nothing to kill or set up kills off a throw". If you meant that there's no options after a throw...DThrow wants a word with you. If you mean there's no combo opportunities besides DThrow, that's not true either. DTilt, for example, leads to similar true combos as DThrow. UAir, like Captain Falcon's UAir, can pop standing opponents up into various other aerial strings or straight into a Helicopter Kick. Heck, even Dash can combo into attacks on bigger characters. UTilt can also combo into itself and other aerials. Plus, you have jab mix-ups with Jab -> Jab -> Throw or Jab -> Jab -> Ultimate Uppercut that either lead to combos or punish characters trying to escape the grab.
Does Mii Brawler have shortcomings? Yeah, reach and lack of safe kill options. Reach especially is an issue. But will that stop Mii Brawler from being, at the least, Top 10? Nah, I personally don't think so. Let his metagame develop, and I think you'll see players use this character properly.
EDIT: Got beaten to the punch, but points still stand!